The invention relates to a piston engine comprising a piston which is movable in a reciprocating manner in a cylinder by means of an electric translatory motor, displaces a gaseous medium and is journalled in a radial direction with respect to the direction of movement of the piston by means of at least one dynamic groove bearing.
The invention further relates to a compression device provided with two piston engines of the aforementioned kind coupled to each other.
The invention also relates to a cryo-cooler comprising a piston engine of the kind already mentioned.
The non-prepublished Netherlands Patent Application No. 8800055, which corresponds to U.S. application Ser. No. 194,763 filed May 17, 1988, discloses a piston engine, a compression device and a cryo-cooler of the kind mentioned in the opening paragraph. The piston engine then forms part of the compression device of a cryo-cooler. In such a piston engine, the electric translatory motor is situated between two dynamic groove bearings, as a result of which a construction of comparatively great length is obtained.